IC-MU_13 Datasheet, PDF (12/59 Pages) IC-Haus GmbH – OFF-AXIS NONIUS ENCODER WITH INTEGRATED HALL SENSORS

iC-MU OFF-AXIS NONIUS ENCODER
WITH INTEGRATED HALL SENSORS
preliminary
PRINCIPLE OF MEASUREMENT
Rev B1, Page 12/59
An absolute position measuring system consists of a
magnetized code carrier and an iC-MU which inte-
grates Hall sensors for signal scanning, signal condi-
tioning, and interpolation in one single device. iC-MU
can be used in rotative and linear measurement sys-
tems.
1
MASTER 16
2
15
3
14
4
13
5
12
6
11
7
10
8
NONIUS
9
TOLtang
CHIP CENTER
POLEDISK CENTER
AXIS CENTER
TOLrad
WOBrad
Figure 5: Rotative position measurement system
Figure 7: Definition of system measurements
Figure 6: Linear position measurement system
Rotative measuring system
The magnetic code carrier consists of two magnetic
encoder tracks. The outer track comprises an even
number of alternately magnetized poles and is used
for high-precision position definition. This is thus called
the master track. The second inside track has one pole
pair less than the outer track and is thus referred to as
the nonius track. This track is used to calculate an ab-
solute position within one revolution of the pole disc.
To this end, the difference in angle between the two
tracks is calculated.
The Hall sensors of iC-MU span one pole pair of the
code carrier. The pole width of the master track is
defined by the distance of the Hall sensors and is
1.28 mm. The position of the sensors on the upper
chip edge has been optimized for 32 pole pairs. Ac-
cordingly, the Hall sensors generate a periodic sine
and cosine signal with a cycle length of 2.56 mm. The
scan diameter can be computed from the number of
pole pairs. The diameter of the pole disc although de-
pends on other mechanical requirements and should
be approx. 3 mm greater than the scan diameter. A
specific diameter for the master and nonius tracks is
derived depending on the number of configured pole
pairs.
The distance between the hall sensors of the non-
ius track and the master track is stipulated as being
3.6 mm by the evaluation device. The scan diameters
of the nonius track can be seen in Table 6.
Number of pole pairs
Master track diameter
Chip center to axis center
Nonius track diameter
Master track pole width
Nonius track pole width
16 32 64
[mm] 13,04 26,08 52,15
[mm] 4,72 11,24 24,28
[mm] 5,84 18,88 44,95
[mm] 1,28 1,28 1,28
[mm] 0,61 0,96 1,12
Linear measuring system
With a linear nonius system the pole width of the mas-
ter track is also 1.28 mm. The pole width of the nonius
track is defined by the number of pole pairs with
Table 6: Pole disc dimensions in mm for rotative sys-
tems
p_nonius
=
1.28 mm
∗
number
number
of
of
poles_master
poles_nonius